AN 974: Intel® Stratix® 10 and Intel Agilex® 7 SmartVID Debug Checklist and Voltage Regulator Guidelines

ID 757318
Date 9/13/2023

1.4. Guidelines: Selecting the Right Voltage Regulator

All SmartVID devices must be driven by the PMBus-compliant voltage regulator, operating either in the master mode or slave mode. Intel® recommends you to use one of the slave device type listed in the drop-down menu in the Intel® Quartus® Prime software that has been tested with the Intel® FPGA tools.

Figure 1.  Intel® Stratix® 10 and Intel Agilex® 7 Voltage Regulator Selection

You can use voltage regulator that are not listed in the GUI by selecting the "Other" option in the Intel® Quartus® Prime software. To choose other voltage regulator, you must ensure the voltage regulator is PMBus-compliant and compatible with the Intel® firmware.

You must ensure that the NVM of the voltage regulator is set correctly. This is to ensure a successful configuration. The following lists the example of NVM setting of the voltage regulator:

  • VOUT_MAX 1.0V
Table 4.  Voltage Regulator Compatibility Check with the Intel® Power Management Firmware
Number Done? Requirement Checklist Item Notes
1   Must PMBus-compliant The chosen voltage regulator must be a 1.3 PMBus-compliant device.
2   Must PMBus commands

The chosen voltage regulator can be operated without requiring any vendor-specific command. All commands must be:

  • Non-write protected
  • No password
  • No special requirement to access
3   Must Configurable

The chosen voltage regulator has a configurable power-on voltage that aligns with the FPGA's data sheet specifications.

Do not require the power management firmware (PMF) to turn it on. The voltage regulator must power up on its own.

Note: The voltage regulator must power up first before starting configuration.
4   Must Noise-resistant and error resetting

The voltage regulator's I2C interface must be resistant to noise1. The voltage regulator firmware must be able to detect noise on the bus and reset without intervention.

Have a message timeout value in the event an incomplete message is received. On timeout, the voltage regulator must flush its input or output buffers and reset the I2C interface.

5   Must Operation mode The voltage regulator must be able to operate in either the direct or linear mode.
6   Must Bit address Supports the 7-bit address.
7   Must Bus speed Supports 100 kHz and 400 kHz.
8   Must Threshold setting Configurable over voltage or current. Configurable under voltage or current.
9   Optional Multi-master compatibility Multi-master mode compatible.
10   Optional Analog-to-digital converter (ADC) sampling rate

The ADC sampling data rate of less than 10 ms without requiring additional command.

Note: If the sampling data rate is more than 10 ms, it can cause configuration error.
Table 5.  Supported PMBus Command
Number Done? PMBus Command Purpose Description Requirement
Master Slave
1   PAGE(00h) Selects the set of voltage regulator control registers This is only required if the voltage regulator has multiple sets of control registers. Optional2
2   VOUT_COMMAND(21h) Sets the voltage

Sets the voltage using either the linear or direct mode format.

This command must not be password protected or require command sequences to send.

This command must use the same encoding or decoding as the READ_VOUT. You must ensure that the voltage regulator has the same resolution as the VOUT or READ_VOUT.

Required Required
3   READ_VOUT(8Bh) Returns the voltage regulator's output voltage

Returns the voltage regulator voltage using either the linear or direct mode format.

This command must use the same encoding or decoding as the VOUT_COMMAND. The voltage regulator must be able to respond to multiple continuous READ_VOUT commands.

4   VOUT_MODE(20h) Returns the mode the voltage regulator uses to report voltage Retrieves the voltage regulator supported VOUT format using either the linear format or direct format. Required Required
5   STATUS_BYTE(78h) Returns the voltage regulator status This command returns one byte of data that indicates the current status of the voltage regulator. For the status byte error message, refer to the respective Power Management User Guide. Required Required
6   CLEAR_FAULTS(03h) Clears any voltage regulator faults This command clears any fault bits that have been set. Required Required
1 Noise can be misinterpreted as commands.
2 Required for multiple rails voltage regulator.

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